Abstract
Saprolegniasis causes significant mortality of fish in aquaculture. Historically, malachite green, formaldehyde, and bronopol have been used to control saprolegniasis. However, their use has either been banned or faced issues with unstable supply chains. Given these limitations, there is a pressing need to develop an alternative chemical solution to prevent this disease effectively. This study focused on glutaraldehyde (GA) as a potential chemical and aimed to assess its effectiveness against various Saprolegnia strains. Seven Saprolegnia strains, including S. parasitica, S. diclina, and S. hypogyna were exposed to GA, malachite green, formaldehyde, or bronopol to evaluate their fungicidal effects. The growth of all tested strains was successfully inhibited by GA at concentrations ranging from 53 to 212 mg/L and temperatures between 10 and 20°C, with a minimum exposure duration of 30 min. The high efficacy of GA indicates its potential for controlling saprolegniasis in fish eggs. Additionally, one strain of S. parasitica was exposed to other aldehyde compounds (formaldehyde, glyoxal, acetaldehyde, isobutyraldehyde, malonaldehyde, or valeraldehyde) to assess the effectiveness of GA based on the presence of the aldehyde group. The fungicidal effects of these compounds were observed at higher concentrations (exceeding 405 mg/L) compared to GA, suggesting that the mere presence of aldehyde groups does not necessarily indicate fungicidal action.
